Efficacy and Safety of Wound Catheter Infusion with Ropivacaine After Abdominal Surgery in Children Aged < 1 Year: A Randomized Controlled Trial.

Background and objective: Wound catheter infusion (WCI) with local anesthetics provides effective postoperative analgesia in adults, without adverse effects on wound healing. Studies on WCI in infants are scarce. The aim of this study was to investigate the efficacy and safety of WCI with ropivacaine as treatment for postoperative pain in infants.

Methods: We conducted a prospective, randomized, double-blind, placebo-controlled trial including children aged < 1 year undergoing open abdominal surgery. Informed consent was obtained. All children received a wound catheter at the end of surgery and were randomized for treatment with either ropivacaine (bolus dose of 2 mg/kg and continuous infusion of 0.2 mg/kg/h) (R-group) or placebo (C-group), for 72 h postoperatively. The C-group received morphine 100 mcg/kg intravenously at the end of surgery, the R-group received placebo. Standard analgesia postoperatively was paracetamol intravenously and rescue morphine intravenously. Primary outcome was the cumulative amount of morphine (mcg/kg) administered in the first 48 hours postoperatively. Secondary outcomes were the number of patients needing morphine, area under the curve over 24 hours of COMFORT-B and Numeric Rating Scale pain scores, incidence of adverse events, and plasma concentrations of ropivacaine.

Results: After inclusion of 30 patients, the study was discontinued because of slow recruitment. In two cases, the wound catheter was accidentally displaced directly after surgery, therefore data of 28 children were analyzed (14 R-group, 14 C-group). Median [interquartile range] cumulative amount of morphine (mcg/kg) administered within 48 hours postoperatively was 0.0 [0.0-642.2] in the R-group, compared with 240.1 [15.1-759.0] in the C-group (P = 0.068). In the R-group, 6/14 children required morphine compared with 13/14 in the C-group (P = 0.013). Pain scores were not significantly different between groups. Plasma concentrations of ropivacaine stayed below toxic thresholds.

Conclusions: Cumulative morphine use postoperatively was not significantly different between infants receiving WCI with ropivacaine or placebo, although a lower number in the R-group required morphine. Wound catheter infusion provided adequate analgesia, with no signs of local anesthetic toxicity. The study may have been underpowered because of early discontinuation.

Clinical trial registration: The study was registered in EudraCT (2015-002209-12), and the Dutch Trial Registry NTR6130 on 23 November, 2016 (International Clinical Trials Registry Platform NL-OMON20504).